In order to drive a screw or other fastener into a substrate, wrenches, such as torque wrenches are often utilized. Torque wrenches are utilized primarily because of their capability to control the amount of torque that can be applied to the fastener while the fastener is being driven into the substrate. Thus, the fastener can be driven into the substrate with the desired level of torque, thereby preventing damage from being done to the substrate as a result of overdriving the fastener into the substrate.
To accomplish this, a number of different torque limiting mechanisms have been developed for implementation within torque wrenches that allow the fastener-engaging portion of the wrench to slip with regard to the driving portion of the wrench when a preset maximum torque value has been exceeded.
However, with the majority of torque limiting mechanisms available, these mechanisms utilize friction as the primary source to develop torque on the mechanism. Therefore, it is desirable to develop an improved torque limiting mechanism that greatly lessens the amount of friction required in order to generate the torque in the torque limiting mechanism, such that the wear on the tool and torque limiting mechanism is reduced, lengthening the life of the tool.
Also, prior torque limiting mechanisms are limited in the amounts of torque value adjustments that can be made as a result of the particular construction of the mechanisms. Thus, it is also desirable to develop an improved torque limiting mechanism that enables finer adjustments of the torque limiting values at which the mechanism can operate.
In addition, a number of wrenches in use employ a ratcheting mechanism to enable the wrench to be used to selectively drive or remove a fastener from a substrate. These mechanisms enable the wrench to be rotated in only one direction, such that the wrench can only be rotated in the direction that either drives or removes the fastener from the substrate as desired.
However, while the ratchet tools currently used in the medical field and in other areas are capable of tightening screws and other fasteners, any prior art ratchet tools suffer from a number of problems that prevent the tools from being utilized most efficiently. One problem is that often times it is difficult for an individual using the ratchet tool to determine when the fastener is tightened to the proper amount based as a result of the construction of the ratchet tool. More specifically, most ratchet tools have a “sloppy feel” as a result of their design, which prevents an individual from feeling the resistance exerted on the tool by the fastener in order to accurately determine when the fastener is properly tightened. Also, when external attachments or shaft couplers are connected to the tool, the loss of feel when utilizing the tool is compounded.
Further, another problem associated with prior art ratchet tools arises due to the positioning of the central gear within the tool. More particularly, when the tool has been used for a certain amount of time, the central gear in the ratcheting mechanism tends to move out of concentricity with the handle of the tool, such that the gear “runs out” with regard to the handle, thereby limiting the effectiveness of the tool.
Finally, another shortcoming of the prior art ratchet tools arises because tools utilized in medical scenarios must be sterilized between uses. Based on the open construction of prior art tools, the use of cleaning solutions to sterilize tools of this type often times cannot adequately clean the internal portions of the tool such that the tool retains dirt or other debris, including residual cleaning fluid, within the interior of the mechanism which can significantly affect the ability operation of the tool to be used.
Therefore, it is desirable to develop a torque wrench tool that includes both an improved torque limiting mechanism optionally in conjunction with an improved ratcheting mechanism to allow for the finer adjustment of the maximum torque values for the tool, as well as enabling the tool to provide adequate feel of the resistance of the fastener through the tool. The improved ratchet tool construction should also effectively prevent any run out of the central gear with respect to the tool, while also effectively sealing off the interior of the tool from the exterior of the tool such that no fluid, gas or debris can get into the tool and affect the operation and/or usefulness of the tool.